Regular Vs Hi-octane

[ahsanonline]

Total charges 90 paisa more than normal per litre

Their website notified rates say 'at no extra charge'. And the rates mentioned there are the same as on Shell's website, and PSO's website.

Can any one explain the relation between high octane and engine compression in detail here?

(In layman terms)
Higher the compression, easier it is for the air-fuel mix to ignite.
Higher the octane number (RON) of fuel, slower it burns.

So, if you put slow burning fuel in high compression engine, its a good match; compare that with a fast burning fuel in a high compression engine, the air-fuel mix will detonate rather than undergo a controlled burn.
On the other hand, if you put a slow burning fuel (higher RON) in a low compression engine, it wont burn fast enough to generate enough power - you'll feel as if the ignition timings are retarded.

Thats why manufacturers specify the fuel to be used with the car, for ideal working, neither knocking to destroy engine, nor running retarded.

[galant1]

Their website notified rates say 'at no extra charge'. And the rates mentioned there are the same as on Shell's website, and PSO's website.

(In layman terms)
Higher the compression, easier it is for the air-fuel mix to ignite.
Higher the octane number (RON) of fuel, slower it burns.

So, if you put slow burning fuel in high compression engine, its a good match; compare that with a fast burning fuel in a high compression engine, the air-fuel mix will detonate rather than undergo a controlled burn.
On the other hand, if you put a slow burning fuel (higher RON) in a low compression engine, it wont burn fast enough to generate enough power - you'll feel as if the ignition timings are retarded.

Thats why manufacturers specify the fuel to be used with the car, for ideal working, neither knocking to destroy engine, nor running retarded.

@xulfiqar @ahsanonline

Okay very easy to understand. As per your described concern, its means the High octane in civic 99 is useless because It slows down engine performance. But I am not fell in lack of power after adding HOBC in my car. Also timing is also retard to end the knocking in my car. Compression ratio is 9.4:1 for d16y5 that I am using in my car. What about your opinion?

[muhammad.hamza.shahid]

good info. thanks.

But, RON varies from 91~100. Depends on country to country, company to company.
Anyone knows the RON value of Pak. hi-octane?

if it varies from counties means hi oct of pak may be equal to regular of other countries
so NO HARM IN DRIVING ON HI OCT
i have a swift 9.5 k on odo, and i drive it soleley on hi octane goes like a rocket, mileage when new (before ffs sfs etc) was 14.6 kmpl @2-3 k rpm
last when driven on high way one side on regular(return trip, oil change etc was due ) gave 12.5 kmpl with full ac and tire pressure 33front 35 rear ... it works just fine, have never put regular in it (unless when availability issues

[Corollarules]

Their website notified rates say 'at no extra charge'. And the rates mentioned there are the same as on Shell's website, and [URL="http://www.psopk.com/"]PSO's .

I have confirmed this my self . Total charges 90 pesa more than PSO. Even the employes of total admit it that thay are charging more. Btw the prices quoted on website are ex depot prices and since petrol price has been deregulated the prices now vary from city to city and from brand to brand.

[tintin1]

This post was flagged by the community and is temporarily hidden.

[muhammad.hamza.shahid]

You are lucky.
As a rough estimate, more than 50% of petrol pumps all over the country are selling regular at the price of hi-octane. It has been observed and proven many times at different occasions.

i only use company operated, pso pumps.

[khalid7shafqat]

Can someone please explain how can high octane fuel result in better mileage. Because i have seen comments against that as well..

[fazalwahab11375]

@umair2203

[tintin1]

This post was flagged by the community and is temporarily hidden.

[khalid7shafqat]

Hioctane's combustion is better than regular. (that’s why It does well the cleaning job for injectors too)
But as the regular petrol is generally of not v. good quality here in Pak. that’s why people mix little hioctane in it. And this hioctane infact improves the better combustion of the regular petrol.
But there are some engines where better combustion is required and hence they perform ideal on Hioctane only. That’s why in USA the petrol pumps has 3~5 types of hioctanes. We are lucky that such cars are rarely available in Pak. yet.
I guess so.

Oh..

I always assumed Hi-octance is the "shashka" petrol. Meaning it is only useful for cars with a higher compression ratio. As this fuel is compressed more.. And we have regular cars mostly, so there wont be any added benefits for us as the compression ratios are not that high..

[deltree]

Just to intrude I am facing knock issues on my JDM Lancer just bought it. And frankly speaking the PSO fill up has not done much it's the first one. So I went up and looked up the real fuel this car needs, so that's basically regular unleaded. According to a JAMA report their Regular Unleaded is 90 RON. So if we do the math 50/50 ratio of hi octane and regular is not one we should be looking for. It's already on Pakwheels through someone's post confirmed by PSO that their hi-octane is 97 RON. Trust me the top end JDM's here would knock like hell worse than our tiny JDM's if hi-octane was any lower.

Anyways the first thing to note is Total Parco's website says they do 90 RON, which pumps is a question mark to me for now.

TOTAL PARCO Pakistan - About us

Now my 11.0:1 compression engine should work nicely on this fuel and if it does bye bye Hi-Octane.

If it does not, I move to my second experiment which is mixing a regular fuel with Hi-Octane to reach a target RON rating of 91-92. If the 90 RON by Total causes knocking means 90 is more like 88-89 thus I will aim at a target ron of 91-92. The effective mix can be done through simple algebraic calculation which I have already done for PSO's ratings which are 87 and 97 RON, so for 40 Litres of fuel you'd need 16 litres of HOBC and 24 litres of regular to reach a 92 RON level.

Paychecks still a little ahead, I will chime in when I have done a fill up at Total, be free to add in the company owned pumps that exist in Karachi (especially DHA/Clifton area).

[deltree]

And for everyone who is wondering what is better for what end, I'd say go for as high a RON rating as you can without going Hi-Octane as long as your car's compression is well within or under 10's. If you have a JDM find out what was the real fuel that was intended for it and then through algebraic calculation find out the mixture of Hi-Octane you need. Their premium is 100 RON regular is 90 RON, japanvehicles.com may have info on fuel type for your car I found mine there.

Regarding fuel efficiency this is the basic rule of thumb, if your car needs a higher ron rating fuel it will give you lower mileage on lower ron rating fuel. I am not sure about feeding higher ron to lower ron desiring cars.

Refer to following JAMA report for more insight:
http://www.acfa.org.sg/pdf/InFocus16_2014_06_JAMA_Towards_95_RON.pdf

[khalid7shafqat]

Just to intrude I am facing knock issues on my JDM Lancer just bought it. And frankly speaking the PSO fill up has not done much it's the first one. So I went up and looked up the real fuel this car needs, so that's basically regular unleaded. According to a JAMA report their Regular Unleaded is 90 RON. So if we do the math 50/50 ratio of hi octane and regular is not one we should be looking for. It's already on Pakwheels through someone's post confirmed by PSO that their hi-octane is 97 RON. Trust me the top end JDM's here would knock like hell worse than our tiny JDM's if hi-octane was any lower.

Anyways the first thing to note is Total Parco's website says they do 90 RON, which pumps is a question mark to me for now.

TOTAL PARCO Pakistan - About us

Now my 11.0:1 compression engine should work nicely on this fuel and if it does bye bye Hi-Octane.

If it does not, I move to my second experiment which is mixing a regular fuel with Hi-Octane to reach a target RON rating of 91-92. If the 90 RON by Total causes knocking means 90 is more like 88-89 thus I will aim at a target ron of 91-92. The effective mix can be done through simple algebraic calculation which I have already done for PSO's ratings which are 87 and 97 RON, so for 40 Litres of fuel you'd need 16 litres of HOBC and 24 litres of regular to reach a 92 RON level.

Paychecks still a little ahead, I will chime in when I have done a fill up at Total, be free to add in the company owned pumps that exist in Karachi (especially DHA/Clifton area).

Bro you are the answer to my cries

Please let us know how the experiment went. so i try it myself

Btw COCO sites, PSO in defense area..

PSO Ittehad
PSO Bhitai (near abdullah shah Ghazi)
PSO MG motors, next to glass tower

last one is recommended

[khalid7shafqat]

And Korangi wala PSO bhi, next to imtiaz super market

[deltree]

And Korangi wala PSO bhi, next to imtiaz super market

I get petrol filled from PSO ittehad, but I think your answer will be delayed a bit. Firstly I got filled Rs. 500 worth of petrol from total pump when my needle was on E. The knocking was 100% the same not even minutely better than at the super from PSO. So I am not 100% sure that total is the answer, so for now since a healthy pay check has come in with arrears (Alhamdulillah) I will first go 100% Hi-Octane from PSO Ittehad today to confirm whether the knocking goes or not if it does means my fuel pump and injectors are fine. I will also record mileage and then move to a mixture in the month's second tank as proposed above.

Update: Filled 100% all knocking gone, but have realized ac is a big problem...taking too much rpm's!

[autotranny]

What about the compression ratio of Corolla SE saloon 2005 engine and whether hi-octane can be useful for that engine ?

[deltree]

Does your car knock on normal fuel?

[khalid7shafqat]

I get petrol filled from PSO ittehad, but I think your answer will be delayed a bit. Firstly I got filled Rs. 500 worth of petrol from total pump when my needle was on E. The knocking was 100% the same not even minutely better than at the super from PSO. So I am not 100% sure that total is the answer, so for now since a healthy pay check has come in with arrears (Alhamdulillah) I will first go 100% Hi-Octane from PSO Ittehad today to confirm whether the knocking goes or not if it does means my fuel pump and injectors are fine. I will also record mileage and then move to a mixture in the month's second tank as proposed above.

Update: Filled 100% all knocking gone, but have realized ac is a big problem...taking too much rpm's!

Okay bro
Keep us posted , can't wait for the results

[ahsanonline]

@deltree
Are you sure your JDM lancer is in good health? No deposits on pistons? If you have a borescope you could peek inside the cylinders and check out engine's guts.
Also check other stuff if you haven't already, such as fuel pressure and fuel trims (if you can get your hands on a scanner).

Is it knocking or just pinging?

[deltree]

@deltree
Are you sure your JDM lancer is in good health? No deposits on pistons? If you have a borescope you could peek inside the cylinders and check out engine's guts.
Also check other stuff if you haven't already, such as fuel pressure and fuel trims (if you can get your hands on a scanner).

Is it knocking or just pinging?

It's the knocking and it's the common knocking I have seen in other lancer threads here just when the car stabilizes at 60km/h for cruising and it's far more than the vitz's/passo's I have seen which knock on acceleration too due to fuel difference. Now about FPR firangi's say it's useless for such stock situations, don't have a scanner but maybe will invest in one down the lane to see what's up. For now Hi-Octane has solved the situation in next tank will try a combo mixture to see if the problem is contained, but if the mixture can't help then I will know something is off because if a end result of RON 90-92 through combination can't help me then something is off.